It is known that hematopoietic malady occurs as a side effect of chemotherapy for hematopoietic organ tumors such as leukemia, etc., and solid tumors, and bone marrow transplant and peripheral blood stem cell transplant are applied as therapies for the hematopoietic malady. These therapies are methods of recovering from hematopoietic malady, in which hematopoietic stem cells and/or hematopoietic precursor cells contained in bone marrow and peripheral blood are transplanted into the human body. By establishing these transplant therapies, chemotherapy for tumors such as leukemia and solid tumors was made feasible. Further, it was found in recent years that hematopoietic stem cells and/or hematopoietic precursor cells are also contained in umbilical cord blood, and therapy by transplanting hematopoietic cells and/or hematopoietic precursor cells from umbilical cord blood is also expected to be a promising method.
Usually, blood used for these transplant therapies is cryopreserved after collecting until transplanting. If cryopreserved blood is contaminated with erythrocytes, the erythrocytes are lyzed to cause side effects after thawing, therefore, before thawing the blood to be transplanted erythrocytes should be removed from the blood.
Known methods of removing erythrocytes from blood to be transplanted include a centrifugation method and a filter method. The centrifugation method utilizes the difference in specific gravity between erythrocytes and leukocytes derived from hematopoietic stem cells and/or hematopoietic precursor cells. The filter method of recovering leukocytes utilizes a filter for passing erythrocytes but capturing leukocytes derived from hematopoietic stem cells and/or hematopoietic precursor cells and the leukocytes captured therein are recovered with a washing solution.
However, the centrifugation method requires such skills as not to cause disturbance of the interfaces among separated blood components, while the filter method has the disadvantage of low yield because the density of the filter material is so high as to capture hematopoietic stem cell- and/or hematopoietic precursor cell-derived leukocytes at high concentrations, thus making it difficult to remove leukocytes which have adhered to the filter material even if a washing solution is used.
The present invention is directed to solving these problems, and an object of the present invention is to provide a filter set for efficiently recovering desired blood components from blood and a method of recovering blood components by use of the filter set.
As a result of their study for achieving the above object, the present inventors found that desired blood components can be efficiently recovered from blood with a blood filter set which comprises a bag body charged with a filter material and an accommodation vessel for accommodating said bag body. Further, they found that a filter set comprises preferably a bag body consisting essentially of a flexible sheet charged inside with a filter material and a rigid accommodation vessel for accommodating the bag body in a compressed condition or in a freely expansive and compressive condition. Additionally, they found that mainly leukocytes could be efficiently recovered from blood by a bag body charged inside with a filter material and a flexible tube body accommodating the bag body in a compressed condition in the thickness direction.